问题补充：
Do you often help your mother?
A. with clean the house
B. cleaning the house
C. to cleaning the house
D. clean the house
答案：
A. with clean the house
B. cleaning the house
C. to cleaning the house
(答案→)D. clean the house
解析：句意：你经常帮妈妈打扫房子吗？固定短语help sb to do sth./do sth.或者help sb. with sth. 故选D.
